Arming device for a fire bomb fuze



June 15, 1965 R. BIANCHI ETAL ARMING DEVICE FOR A FIRE BOMB FUZE z Sheets-Sheet 1 Filed Oct. 28, 1955 P0 TE IV T/AL SOURCE A ND GOIV TROL PANEL INVENTORS R. BIANCHI A. S. WILL N. C. BUTLER June 15, 1965 Filed Oct. 28, 1955 FIG. 3

R. BIANCHI ETAL ARMING DEVICE FOR A FIRE BOMB FUZE z Sheets-Sheet 2 INVENTORS R. BlANCHl A. S. WILL N. C. BUTLER 3,133,953 ARMING DEWQE FOR A FIRE 39MB FUZE Renato Bianchi, Beltsville, Albert S. Will, College Paris,

and Norman Q. Butler, Silver Spring, Md, assignors to the United States of America as represented by the Secretary of the Navy Filed Get. 23, 1955, Ser. No, 543,636 9 Claims. (Cl. 1022) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to an ordnance device adapted to be launched from an aircraft in flight and more particularly to new and improved fuzing arrangement for a fire bomb.

Fuzing arrangements operable by mechanical means, electrically energized circuitry, or a combination of both, have long been known and used. These prior art devices, however, do not include certain safety features required by the armed forces for use in service. Moreover, such devices lack desirable remote control features and easy adaptation to the severe streamlined operation required of present day high speed aircraft.

The present invention possesses all the advantages of the prior art devices and is constructed and arranged to overcome all the disadvantages possessed by such prior art devices by providing a new and improved fuzing arrangement having the desired safety features for arming and firing a fire bomb.

Modern fire bombs require a fuze having a safety device, such as an out-of-line explosive train. The safety device, for example, is responsive to a predetermined sequence of operations and, unless this sequence of operations is fulfilled, arming and subsequent detonation or ignition of the bomb is prevented. The device of the present invention provides a fire bomb train fuzing arrangement in which the above mentioned requisites have been found to be satisfactory.

Moreover, through actual experience it has been found that an electrically operable fuzing arrangement for a fire bomb should include the following features of importance:

(1) Means for the prevention of premature arming and resultant ignition of the bomb in order to insure safety to the launching aircraft.

(2) Severable means interconnecting the launching aircraft and the bomb fuze adaptable to modern streamlined plane and fire bomb design.

(3) Means whereby, when the bomb has been launched from an aircraft under normal conditions, ultimate ignition of the bomb is assured.

In the electrically operated fuzing arrangement for fire bombs according to the present invention, all of the above features have been provided. The primary electrical energy input to the fuzing device cannot be connected therethrough until the bomb has been released from the supporting rack or shackle on the aircraft and has fallen free to the extent of the length of a severable flexible charging connection; and further, the arming of the bomb does not occur until the expiration of a fixed time delay after the instant the bomb has fallen free to the extent of the length of the aforesaid flexible charging connection. When the fixed time delay period has expired, a primer means moves into alignment with the main inflammable charge of the bomb and concurrently therewith, the primer and an impact operable switch are serially connected in a circuit including a source of stored electrical energy. Thus, the primer will be fired and bring about a resultant ignition of the bomb upon impact of the bomb with a target.

Bdhfifiiid. Patented June 15, 1965 The preferred embodiment of the invention includes a source of electrical energy carried by the aircraft, a fiexible potential carrying cable interconnecting the source and the bomb fuze and an electrical circuit including arming means disposed within the bomb casing adapted to be interconnected with the flexible potential carrying cable.

The circuitry and associated equipment further includes a plurality of switches, one of which is operated by a firing of a pyrotechnic delay squib, and another of which is operable by the movement of a plunger actuated by means contained within the connecting plug for the flexible potential carrying cable. The pyrotechnic squib, in addition to operating a switch, also mechanically aligns the primer means with the conventional main inflammable charges of the bomb. The circuitry also includes a capacitor means which stores the electrical energy received by the bomb fuze from the source after the bomb is launched, and an impact actuated or jiggle switch.

An object of the present invention is to provide a new and improved fuzing arrangement for a fire bomb.

Another object of the invention is the provision of a fuzing structure including means externally indicative of the bomb as to the relative position of the main arming means and, at the same time, provide a mechanical interlock whereby the arming of the bomb is prevented during a fixed delay period subsequent to the launching of the bomb from an aircraft.

A still further object is to provide a fuzing arrangement for a fire bomb in which an impact received by the bomb during the fixed delay will prevent subsequent detonation or ignition of the bomb and thus render the same safe for disposal.

Other objects and many of the attendant advantages of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a central longitudinal sectional view of the arming switch constructed in accordance with the present invention including suitable circuitry therefor;

FIG. 2 is a view similar to FIG. 1 with the switch in a position for momentarily supplying a firing impulse to the time delay explosive device; and,

FIG. 3 is a view similar to FIG. 2 with the switch in a position for momentarily supplying a charge to the electrical energy storage device.

Referring now to the drawings and more particularly to FIG. 1 thereof the numeral 1ft generally indicates an arming switch and the numeral ll designates an electrical potential source such, for example, as a battery or the like carried by the aircraft and which may, if desired, be connected through normally open contacts (not shown) associated with the bomb rack or the potential source may be connected directly to a connector 12 as shown and by way of a flexible electrical conductor 14 having a flexible electrical conducting shield 2t? thereabout and insulated therefrom, to the contact surfaces 15 and 16 carried by a plunger 17 contained within the fuze plug 18 of the switch It and secured to the other end of the flexible conductor 14. It will be understood that the normally open contacts heretofore mentioned as being associated with the bomb rack, when utilized, are arranged in such a manner that they move to a closed position only when the bomb is released from the rack and falls away from the aircraft.

The electrical circuitry generally indicated by the reference character 19 is disposed within the bomb and connected to brushes 2122 secured to the fuze plug 18. it will be understood that the electrical circuit operation is initiated by the pilot as the bomb is released from the aircraft and the circuit is completed after the bomb has traveled a predetermined distance therefrom. When this occurs the flexible conduit comprising the conductor 14 which is secured to the plunger causes axial movement of the plunger outwardly and concurrently therewith the contact surfaces 15 and 16 are moved proportionally thereto. The movement of the contacts 153l5 selectively closes connections with the brushes 22-21, the contact 16 being insulated from the plunger.

The fuze also comprises a mechanical interlock between the plunger 17 and the means for aligning the primer of the fuze. It will be noted that the pyrotechnic delay squib 23 is adapted to move contacts 24-25 associated with the circuitry of the fuze and drive a shaft 26 through rack 27 and pinion 28. The shaft 26 has secured thereto a disc 29 having a notch 31 formed in the periphery thereof for receiving a rod 32 forming a part of the plunger 17 thereby to prevent premature rotation of the shaft. Shaft 26 has mounted thereon and secured thereto a member or arming rotor 33 having an electroresponsive primer 34 arranged therein, the primer being normally out of alignment with the conventional initiating main inflammable charge (not shown). By this arrangement it will be understood that should the squib 23 be prematurely fired, the primer 34- will be prevented from rotating to an armed position by reason of the aforesaid locking arrangement including the disc 29 and 7 rod 32. The plunger 17 is maintained in its initial position, FIG. 1, by a shear pin 35 extending through an enlarged flange member 36 formed with the plunger 17 and a pair of oppositely disposed openings 37 whereupon brushes ZLZZ are maintained in engagement with the elongated contact 15 on the plunger 17.

In addition to the foregoing safety features, the electrical circuitry within the bomb is maintained at a zero or neutral potential while the plunger is held in its initial position by the shear pin 35. As more clearly shown on FIG. 1 the flexible cable 14 and plunger are detachably secured to a plug 13 threadedly secured to connector 12 by any suitable separable means, such for example, as the frangible metallic Washer illustrated in engagement with the end wall 38 of the plug and disposed between the wall 38 and an enlarged flange 39 formed on the plunger 41. The end Wall 38 is provided with an aperture 47 of greater diameter than the flange 39, for a purpose which will become more clearly apparent as the description proceeds. The relation between the tensile force necessary to rupture'the frangible washer 4t and the aforesaid shear pin 35 is preferably in the .order of 5 or 6 to 1 respectively. The specific use which is made of these proportional rupturing forces will be more fully described as the description proceeds.

It will be understood that the element 12 is secured to the aircraft in any suitable manner and threaded into the plug 13 as at 42, the arming switch 18 being threaded into the bomb 3% as at 43 When the bomb is attached to the aircraft it will be noted, FIG. 1, that the end portion of plunger ell is disposed within a socket 44 composed of insulating material and formed in the connector 12 with the contact 45 carried thereby insulated from the element 12 and in engagement with a contact member 46 carried on the end portion of plunger 41 and in electrical connection with the flexible conduit 14 whereupon electrical energy may be supplied to the circuitry of the fuze after the bomb is released from an aircraft in flight and traveled a predetermined distance therefrom thereby to arm the fuze. The flexible conductor 14 and shield 20 possess considerable strength and are secured to plungers 17 and 41 in such manner that the plungers will not be detached therefrom in service.

Although the drawing illustrates a single insulated hot wire for the electrical circuitry with the other side thereof grounded, it will be apparent, if desired, that a second insulated conductor may be employed in lieu of the ground connection.

The operation of the device Will now be described in engagement with the end wall 4) on casing 18.

(3}, detail. When the bomb is released from an aircraft in flight, the pilot energizes by suitable means on the control panel connected to the potential source 11, the connector 12, it being understood that while only one such connector is illustrated it is the usual practice in fire bombs to employ at least two of such devices and circuitry arrangement. It will be noted, FIG. 1, that one side of the circuit extends from the source 11 to the insulated contact 45 carried by connector 12, contact member 46 carried by member 41, flexible electrical conductor 14 secured thereto, and thence to the insulated movable contact 16 on the plunger 17. The other or ground side of the circuit is completed through the aircraft frame and the components parts of the connector 12, and thence to the member 18 and the uninsulated contact 15 on plunger 7. it will be noted that both of the brushes 2-1-22 are normally in engagement with the grounded or neutral contact 15 whereupon the circuitry of the fuze will not be energized until the plunger is moved a predetermined amount such, for example, as shown on P165. 2 and 3.

When the bomb is released from the aircraft and falls free and by reason of the length of the flexible conductor 14 movement of the plunger 17 within casing 18 will not occur. When the distance of the free fall of the bomb, however, exceeds the length of'the flexible conduit, tension exerted on the conduit will sever the shear elemeat 35 since it has a relatively lower breaking point than the frangible washer 4i) and thus plunger is moved progressively within the casing 18. As the plunger is progressively moved, contact 16 will move into engagement with brush 22., thereby applying a potential through conductor 48 to the pyrotechnic delay squib 23 and thence to ground whereupon the squib is fired when a predetermined period of time has elapsed. The relative position of the brushes and contacts 1516 at this time is illustrated on FIG. 2 and the plunger rod or extension 32 is withdrawn from notch 31 in disc 29, releasing the shaft 26, the aforesaid rack and pinion being actuated as the squib is fired thereby to rotate the shaft 26 an amount suflic-ient to align the primer 34 with the inflammable or explosive charge of the bomb, as the case may be. The delay inherent to the firing of the squib 23, however, is sufficient to permit the aircraft to be at a point well beyond the lethal range of the bomb such, for example, as 2 /2 seconds.

As the bomb continues to fall away from the aircraft, the plunger 17 is further progressively moved within the casing 18, and contact 16 passes beyond brush 22 breaking the circuit to squib 23 and moving into engagement momentarily with brush 21, thereby transferring the potential received from the aircraft to condenser C Whereupon the condenser is charged an amount suflicient to cause functioning of the fuze .in response to impact of the bomb with a target. The relative position of the brushes and contacts within the casing 18 at this time is illustrated in FIG. 3.

Continued movement of plunger 17 due to the free fall of the bomb, causes contact 16 to pass beyond brush 21 thereby breaking the charging circuit to condenser C and the enlarged flange 36 on the plunger moves into When this occurs the tension due to falling of the bomb is transferred through the flexible conductor 14 and the shield 20 to the frangible washer 4t) disposed within the member 13 and arranged between the end Wall 38 on member 13 and the flange 39 on plunger 41. As the weight of the bomb is exerted on the frangible Washer 40, the washer is severed, andthe plug end 4-1 is disengaged from socket 44 in connector 12 and the enlarged head 39 thereof passes through aperture 47.

The electrical charge impressed on condenser C as the aforesaid manner eventually causes the ignition of the maininflammable charge of the bomb. Should the bomb undergo an impact prior to the firing of the delay squib 23, the impact switch I will cause condenser C 'to be discharged by way of ground connections, condenser 23, conductor 51, impact switch I, closed contact controlled by rack or actuating bar 27 and conductor 52 and thence to ground.

When the squib 23 has been fired, the switch arm 24 secured to the rack bar 27 is moved into engagement with contact 55 thereby completing a firing circuit from the condenser C to electroresponsive primer 34 and prior thereto the switch arm 25 is moved out of engagement with contact 56 thereby unshorting the primer 34 and thus the fuze is rendered eifective to be fired in response to impact of the bomb with a target. The firing circuit is completed by way of ground, condenser C, conductor 51, impact switch I, conductor 52, switch arm 24, contact 55, conductor 57, primer 34- and thence to ground.

From the foregoing, it will be apparent that the present invention contemplates the provision of new and improved mechanical safety features and interlocks for use in a fire bomb including a fuze constructed in such a manner that the electrical circuitry contained therein has a neutral or grounded potential when the component parts thereof are assembled and interconnected. Moreover, the circuitry provides an additional safety feature in that static or leakage charges received from the source of electrical energy may not produce a prematurely armed bomb, and ignition of the main inflammable charge of the bomb will not occur until the aforesaid sequence of operation has been completed.

Obviously many modification and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise that as specifically described.

What is claimed as new and desired to be Letters Patent of the United States is:

1. In a system for arming an airborne fire bomb in time delayed relation with respect to the release of the bomb from an aircraft, in combination, a source of electrical energy in the aircraft, a bomb, a switch mechanism mounted in said bomb, means for releasably connecting the switch mechanism to said source, a normally locked switching element arranged for movement within said switch mechanism and movable therein, means for moving said element as the bomb is released from the aircraft and falls away therefrom a predetermined amount, means including a shear pin carried by said element and attached to said switch mechanism and in a manner to be sheared as the bomb falls away from said aircraft said predetermined amount, normally locked arming means rotatably supported within said bomb and movable from an initial safe position to an armed position when released, means on said element for releasing said arming means when the element is moved said predetermined amount, driving means connected to said arming means and actuated by an explosive force applied thereto for moving the arming means from said initial safe position to said armed position, a normally interrupted control circuit, time delay explosive means in said circuit and fired in response to an electrical impulse received thereby for applying said explosive force to said driving means as said normally interrupted control circuit is rendered effective, means included in said circuit for rendering said circuit effective as the switching element is moved said predetermined amount, electrical energy storage means, a normally interrupted charging circuit for said storage means, means included in said charging circuit for rendering the charging circuit effective to charge said storage means as the switching element is moved an amount, greater than said predetermined amount and means including a frangible element for thereafter disconnecting said switch mechanism from said source.

2. A system according to claim 1 and including an electroresponsive primer arranged within said arming means, a normally interrupted firing circuit connected to said secured by storage means, and a normally open impact responsive device included in said firing circuit for discharging said energy through said primer sufiicient to fire the primer as said impact responsive device is actuated to a closed position upon impact of the bomb with a target thereby to explode the bomb.

3. In a device for arming an airborne fire bomb in time delayed relation with respect to the release of the bomb from an aircraft, in combination, a source of electrical energy in the aircraft, a connector secured to the aircraft and connected electrically to said source, a bomb, a switch mechanism mounted in said bomb and releasably connected to the connector, a normally locked switching element arranged within said switch mechanism and movable therein as the bomb is released and falls away from the aircraft, a shear pin carried by said element and connected to said switch mechanism in a manner to be sheared as the bomb falls away from the aircraft a predetermined amount for releasing said element, normally locked arming means rotatably supported within said bomb and movable from an initial safe position to an armed position when released, a disc carried by said arming means and having a notch formed in the periphery thereof, a rod formed on said switching element and H initially disposed within said notch for releasing said arming means when the element is moved said predetermined amount, driving means including a pinion mounted on said arming means and actuated by an explosive force applied thereto for moving the arming means from said initial safe position to said armed position, a normally interrupted control circuit, time delay explosive means in said circuit and fired by an electrical impulse received thereby for applying said explosive force to the drivin means as said control circuit is rendered effective, contact means carried by said switch mechanism and included in said circuit for rendering said circuit effective as the switching element is moved said predetermined amount, electrical energy storage means, a normally interrupted charging circuit for said storage means, add-itional contact means carried by said switch mechanism for rendering the charging circuit effective to charge said storage means as the switching element is moved an amount greater than said predetermined amount, means including a frangible element disposed within said connector for disconnecting the switching mechanism from said source after the switching element has moved an amount greater than said predetermined amount, and means including an electroresponsive primer arranged within said arming means for exploding the bomb in response to impact of the bomb with a target.

4. In a system for arming an airborne fire bomb time delayed relation with respect to the release of the bomb from an aircraft, in combination, a source of electrical energy arranged within the aircraft, a connector secured to the aircraft and electrically coupled to said source, a switch casing carried by and secured to said bomb, a normally locked plunger arranged within said casing and movable therein as the bomb is released and falls away from said aircraft, means including a flexible conductor carried by said plunger for electrically coupling said plunger to said connector, a shear pin mounted on said plunger and connected to said casing in a manner to be sheared as the bomb falls away from the aircraft a predetermined amount for releasing said plunger, a normally locked shaft rotatably supported within said bomb, a disc secured to said shaft, a rod formed on said plunger in locking engagement with said disc for preventing rotation of said shaft until said plunger has been moved said predetermined amount, a pinion secured to said shaft for rotating said shaft when the shaft is released and the pinion is rotated, a rack bar in engagement with said pinion and actuated by an explosive force applied thereto for rotating said pinion, a normally interrupted control circuit, clectroresponsive time delay explosive means in said circuit and fired by an electrical impulse received thereby for applying said explosive force to said rack bar as said circuit is rendered effective, means including a Contact element actuated by said plunger and connected to said flexible conductor for rendering said circuit effective as the plunger is moved said predetermined amount, electrical energy storage means, a normally interrupted charging circuit, contact means carried by said casing and included in said charging circuit for rendering the charging circuit effective to charge said storage means as the plunger is moved an amount greater than said predetermined amount and said contact element engages said contact means, an electroresponsive primer carried by said shaft and rotated from an initial safe position to an armed position as said shaft is released and rotated a predetermined amount, a firing circuit, and impact responsive circuit closing means included in said firing circuit for discharging said energy through the primer upon impact of the bomb with a target thereby to fire the primer and explode the bomb.

5. In a device for arming an airborne fire bomb in time relayed relation with respect to the release of the bomb from an aircraft in flight, in combination, a source of electrical energy in the aircraft, a connector secured to the -aircraft and connected to said source, a switch mechanism carried by said bomb and releasably attached to said connector and to the source, a normally locked switching element disposed 'Within the switch and'movable a predetermined amount as the bomb is released and falls away from the aircraft, normally locked arming means rotatably mounted in the bomb and movable from an initial position to an armed position when released, means on said element for releasing the arming means when said element has been moved said pr determined amount, actuating means inciuding a rack bar connected to the arming means for moving the arming means from said initial safe position to said armed position in response to an explosive force applied thereto, means including a delay element fired in response to an electrical impulse applied thereto for applying said explosive force to said actuating means, means on said switch in a manner to be engaged by said switching element when the element is moved said predetermined amount for applying said impulse to said delay element, an electrical energy storage device, means on said switch and adapted to be engaged by the switching element when the element is moved an amount greater than said predetermined amount for applying a charge on the storage device, an electroresponsive primer arranged within said arming means and rotatable to said armed position thereby, and means including an impact responsive circuit closing device for discharging said energy through said primer upon impact of the bomb'with a target thereby to fire the primer and explode the bomb.

6. In a device for arming an airborne fire bomb in time delayed relation with respect to the release of the bomb rom an aircraft in flight, in combination, a source of electrical energy in the aircraft, a connector secured to the aircraft and connected to said source, switch means carried by said bomb, a normally locked movable switching element disposed within said switch means, means for electrically connecting the switching element to said connector, shearable means carried by said element and attached to said switch means in a manner to be sheared as the bomb is released and falls away from the aircraft for releasing said element for sliding movement Within the switch means, normally locked arming means rotatably mounted in the bomb and movable from an initial safe position to an armed position when released, means on said element for releasing said arming means when the ele ment has been moved a predetermined amount, actuating means connected to said arming means and movable in response to an explosive force applied thereto for moving the arming means from said initial safe position to said armed position, a normally interrupted control circuit connected to said switch, means including a delay element in said circuit and fired in response to an electrical impulse applied thereto for applying said explosive force to the actuating means, contact means in said circuit and engaged by the element when the element is moved said predetermined amount for applying said impulse to the delay element, a normally interrupted charging circuit, electrical storage means included within said charging circuit and charged through said element from said source when the element is moved an amount greater than said predetermined amount, an electroresponsive primer dis posed within said arming means and movable to an armed position thereby, a firing circuit, and an impact responsive circuit closing device in said firing circuit and connected to said storage means for discharging said energy through the primer upon impact of the bomb with a target thereby to firethe primer and explode the bomb.

7. A switch for completing momentarily an electrical path through a pair of normally interrupted control circuits in successive order in such manner that one of said circuits is interrupted after closure thereof before the other of the circuits is closed comprising a casing, a normally locked switching element disposed within said casing,'a frangible pin carried by said element and attached to the casing for releasing the element for sliding movement as said frangible pin is severed in response to an external force applied thereto, a contact on said element and insulated therefrom, a flexible electrical conductor disposed within the element and insulated therefrom and connected to said contact and to an external source of electrical energy, a flexible metallic shield encircling said conductor and connected to said element for moving the element within said casing, a first contact member on said casing for completing an electrical path through one of the control circuits as the element is moved a predetermined amount and said contact moves into engagement with said first contact member, and a second contact member on said casing in spaced relation with respect to said first contact member for completing an electrical path through the other control circuit as the element is moved an amount sufficiently greater than said predetermined amount for the contact to be disengaged from said first contact member and brought into engagement with the second contact member.

8. In a system for arming an airborne fire bomb in time delayed relation with respect to the release of the bomb from an aircraft in flight, in combination, a source of electrical energy in the aircraft, a switch mounted in said bomb, means for releasably connecting the switch to said source, a normally locked switching element disposed within said switch and movable therein by said last named means as the bomb is released from the aircraft and falls away therefrom a predetermined amount, frangible means carried by said element and attached to said switch in a manner to be sheared as the bomb falls away from the aircraft said predetermined amount, normally locked arming means rotatably supported within the bomb and movable from an initial safe position to an armed position when released, means on said element for releasing said arming means when the element is moved said predetermined amount, a pinion on said arming means, a rack bar in engagement with said pinion and actuated in response to an explosive force applied thereto for moving the arming means from said initial safe position to said armed position, a normally interrupted control circuit, time delayed explosive means in said circuit and fired in response to an electrical impulse received thereby for applying said explosive force to said rack bar as said normally interrupted circuit is rendered effective, means comprising a contact carried by said switch and included in said circuit for rendering the control circuit effective as the switching element is moved said predetermined amount.

9. In a system for arming an airborne fire bomb in time delayed relation with respect to the release of the bomb from an aircraft in flight, in combination, a source of electrical energy in the aircraft, a switch casing secured to said bomb, a normally locked plunger disposed Within the casing and movable within the casing when released, frangible means carried by said plunger and attached to said casing in a manner to be sheared as the bomb is released from the aircraft and falls away therefrom a predetermined amount, normally locked arming means rotatably supported within the bomb and movable from an initial sate position to an armed position when released, a rod on said plunger in locking engagement with the arming means for releasing said arming means when the plunger is moved a predetermined amount, a pinion on said arming means, a rack bar in engagement with said pinion and actuated by an explosive force applied thereto for moving the arming means from said initial safe position to said armed position, a normally interrupted control circuit, an electroresponsive time delay element in said circuit and fired in response to an electrical impulse received thereby for applying said explosive force to said rack bar as said control circuit is rendered effective, a contact on said References Cited by the Examiner UNITED STATES PATENTS 1,897,863 2/33 Ruhlemann 102-70.2 2,249,977 7/41 Penfold 200-464 X 2,276,378 3/42 Duguay 200-164 X BENJAMIN A. BORCHELT, Primary Examiner. SAMUEL BOYD, ARTHUR M. HORTON, Examiners. 

1. IN A SYSTEM FOR ARMING AN AIRBORNE FIRE BOMB IN TIME DELAYED RELATION WITH RESPECT TO THE RELEASE OF THE BOMB FROM AN AIRCRAFT, IN COMBINATION, A SOURCE OF ELECTRICAL ENERGY IN THE AIRCRAFT, A BOMB, A SWITCH MECHANISM MOUNTED IN SAID BOMB, MEANS FOR RELEASABLY CONNECTING THE SWITCH MECHANISM TO SAID SOURCE, A NORMALLY LOCKED SWITCHING ELEMENT ARRANGED FOR MOVEMENT WITHIN SAID SWITCH MECHANISM AND MOVABLE THEREIN, MEANS FOR MOVING SAID ELEMENT AS THE BOMB IS RELEASED FROM THE AIRCRAFT AND FALLS AWAY THEREFROM A PREDETERMINED AMOUNT, MEANS INCLUDING A SHEAR PIN CARRIED BY SAID ELEMENT AND ATTACHED TO SAID SWITCH MECHANISM AND IN A MANNER TO BE SHEARED AS THE BOMB FALLS AWAY FROM SAID AIRCRAFT SAID PREDETERMINED AMOUNT, NORMALLY LOCKED ARMING MEANS ROTATABLY SUPPORTED WITHIN SAID BOMB AND MOVABLE FROM AN INITIAL SAFE POSITION TO AN ARMED POSITION WHEN RELEASED, MEANS ON SAID ELEMENT FOR RELEASING SAID ARMING MEANS WHEN THE ELEMENT IS MOVED SAID PREDETERMINED AMOUNT, DRIVING MEANS CONNECTED TO SAID ARMING MEANS AND ACTUATED BY AN EXPLOSIVE FORCE APPLIED THERETO FOR MOVING THE ARMING MEANS FROM SAID INITIAL SAFE POSITION TO SAID ARMED POSITION, A NORMALLY INTERRUPTED CONTROL CIRCUIT, TIME DELAY EXPLOSIVE MEANS IN SAID CIRCUIT AND FIRED IN RESPONSE TO AN ELECTRICAL IMPULSE RECEIVED THEREBY FOR APPLYING SAID EXPLOSIVE FORCE TO SAID DRIVING MEANS AS SAID NORMALLY INTERRUPTED CONTROL CIRCUIT IS RENDERED EFFECTIVE, MEANS INCLUDED IN SAID CIRCUIT FOR RENDERING SAID CIRCUIT EFFECTIVE AS THE SWITCHING ELEMENT IS MOVED SAID PREDETERMINED AMOUNT, ELECTRICAL ENERGY STORAGE MEANS, A NORMALLY INTERRUPTED CHARGING CIRCUIT FOR SAID STORAGE MEANS, MEANS INCLUDED IN SAID CHARGING CIRCUIT FOR RENDERING THE CHARGING CIRCUIT EFFECTIVE TO CHARGE SAID STORAGE MEANS AS THE SWITCHING ELEMENT IS MOVED AN AMOUNT, GREATER THAN SAID PREDETERMINED AMOUNT AND MEANS INCLUDING A FRANGIBLE ELEMENT FOR THEREAFTER DISCONNECTING SAID SWITCH MECHANISM FROM SAID SOURCE. 